Investigation towards Isolated Epoxy Impregnated REBCO Windings

This work presents the development and characterisation of an 11-turn REBCO coil. The coil was dry-wound on a G10 former with copper electrodes and ultra-thin 30 micron-thick glass fibre insulation to compensate for the lack of mechanical stability offered by alternative insulations, while still enabling complete vacuum resin impregnation of the coil. Prior to coil fabrication, transport measurements were performed on single-tape and insulated tape-stack samples to evaluate the electrical and thermal performance of the REBCO tape under the influence of self-generated magnetic fields with different current configurations at 77 K. As expected, the self-field significantly affected the parallel configuration. However, a notable and unexpected reduction in critical current was also observed in the antiparallel configuration. Data from short-tape experiments were used to inform simulations of the coil, providing theoretical performance predictions that were later compared with the actual performance of the fabricated coil. The coil itself was designed and wound, and its thermal and electrical behaviour was analysed by experiments conducted at both 77 K and 65 K. The coils electrical performance seemed to match the simulation results reasonably well, lending encouraging support to the insulation/impregnation strategy and an operational reliability upon multiple quenches and thermal cycles. Furthermore, the fully impregnated structure improves coil handleability for future integration into larger machines compared to non-insulated coils with little to no penalty in performance.